From: Andrew Warkentin <andreww591@gmail.com>
To: The Unix Heritage Society <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] Pre-init initialization
Date: Tue, 6 Aug 2019 19:22:08 -0600 [thread overview]
Message-ID: <CAD-qYGq4CZO=B5Un-wT6MV8-=XiMR=08zaqbqW4R0rhhLTaTMA@mail.gmail.com> (raw)
In-Reply-To: <7236c9d4-40af-bc49-8aee-5c32d869d2eb@spamtrap.tnetconsulting.net>
On 8/6/19, Grant Taylor via TUHS <tuhs@minnie.tuhs.org> wrote:
> Do, or did, anything other than Linux use a concept of an initramfs /
> initrd to create a pre-(main)-init initialization environment to prepare
> the system to execute the (main)-init process?
>
Off the top of my head I'm not aware of any other conventional Unix
besides Linux that uses a memory filesystem for early userspace.
Solaris does use a memory filesystem during boot, but it normally
contains only kernel modules and is only read by the kernel module
linker, and IIRC AIX uses a weird vaguely zImage-like format for its
boot image but I can't remember if the image contains just the kernel
and some modules or if there are userspace programs in it.
As far as unconventional Unix-like OSes go, QNX Neutrino (but not QNX
2 and 4) and Plan 9 both use in-memory filesystems during early
userspace boot, although both only load a single image from disk
rather than a separate kernel and ramdisk. In QNX, the image is a
page-oriented XIP filesystem that contains the kernel and early
userspace as regular files, and in Plan 9 the image is the kernel
executable, which contains a minimal embedded filesystem with a few
user-mode programs.
UX/RT, the OS that I'm writing, will also boot from a memory
filesystem containing the kernel and early userspace in a similar
manner to QNX (it's loosely based on QNX and Plan 9 but is not a clone
of either), although currently it isn't running any real userspace
programs.
next prev parent reply other threads:[~2019-08-07 1:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-06 23:46 Grant Taylor via TUHS
2019-08-07 1:22 ` Andrew Warkentin [this message]
2019-08-07 13:04 ` Clem Cole
2019-08-07 16:40 ` Warner Losh
2019-08-08 13:31 ` Theodore Y. Ts'o
2019-08-09 1:52 ` Grant Taylor via TUHS
2019-08-10 0:23 ` Theodore Y. Ts'o
2019-08-10 2:28 ` Grant Taylor via TUHS
2019-08-10 4:21 ` Kevin Bowling
2019-08-10 4:50 ` Grant Taylor via TUHS
2019-08-10 4:52 ` Adam Thornton
2019-08-08 13:43 ` Clem Cole
2019-08-08 18:59 ` Warner Losh
2019-08-09 1:46 ` Grant Taylor via TUHS
2019-08-09 2:15 ` Warner Losh
2019-08-09 6:43 ` Kevin Bowling
2019-08-10 1:45 ` Chris Hanson
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